1. Field of the Invention
The present invention relates to a method of designing a golf club head and the golf club head. More particularly, the present invention is intended to decrease the backspin amount of a golf ball and increase the hitting angle thereof by analyzing the situation of contact between the golf club head and the golf ball in a computer when the golf club head impacts against the golf ball, and altering the thickness, material, and configuration of the golf club head in the computer. Especially, the present invention is intended to efficiently design a golf club head which can be suitably used for low-number woods' head and low-number irons' head.
2. Description of the Related Art
It is very important to design a golf club head so that the golf club head is capable of hitting the golf ball a long distance efficiently, although there is a difference in the flight distance of the golf ball in dependence on the kind and the number of a golf club.
It is known that a wood club head and a low-number iron club head demanded to have performance of hitting the golf ball a long distance are capable of doing so efficiently, if they are capable of decreasing the backspin amount of the golf ball and hence increasing the hitting angle thereof.
On the other hand, it is known that high-number iron clubs demanded to have high controllability of the golf ball while maintaining performance of hitting the golf ball to some extent are capable of doing so efficiently, if they are capable of increasing the backspin amount of the golf ball.
Various proposals have been made on the relationship between the backspin of the golf ball and the flight distance thereof as well as the golf club head which impacts against the golf ball. As disclosed in Japanese Patent Application Laid-Open Nos. 2001-346907 and 2002-263216, the present applicant proposed a golf ball having the construction in which the force acting in the backspin-decreasing side during the contact between the golf club head and the golf ball is relatively increased to decrease the backspin amount and make the hitting angle large.
As disclosed in Japanese Patent Application Laid-Open No. 11-253584, the present applicant also proposed a set of iron club heads in which the surface condition of the face of the iron club head is controlled to increase the coefficient of friction between the golf ball and the head by roughening the surface of the golf club head. Thereby the force acting in the backspin-decreasing side during the contact between the golf club head and the golf ball is relatively increased to decrease the backspin amount and make the hitting angle large. It is disclosed in the patent document 3 that the set of iron club heads is particularly effective when the heads are used for golf clubs whose lofts are less than 30 degrees.
However, even though the golf ball disclosed in the patent documents 1 and 2 has excellent performance, it is conceivable that there is a difference in the degree of the effect of the excellent performance of the golf ball in dependence on the construction of a golf club head which strikes against the golf ball. As described above, it is preferable to hit the golf ball with a golf club head capable of decreasing the backspin. But it is not easy to estimate a golf club head having a construction suitable for the golf ball disclosed in the patent documents 1 and 2.
In the set of the iron club heads disclosed in the patent document 3, the friction coefficient of the face of the head is altered according to the number of a golf club, and the backspin amount is adjusted in dependence on the number of the golf club. Only specifying the friction coefficient is insufficient for driving the golf ball a long distance. The condition of the face of the head may change as the head impacts against the golf ball repeatedly. Therefore there is room for improvement to hit the golf ball a long distance stably.
To grasp the relationship between the backspin amount of the golf ball and the golf club head which strikes against the golf ball, it is necessary to make a large number of heads and the like on an experimental basis and measure the backspin amount by making experiments. But much labor and cost are required to make such a trial manufacture. In addition, apparatuses having complicated constructions are required to measure a frictional force and the like necessary for analyzing the backspin at the time of impact of the golf club head against the golf ball. Further it is very difficult to measure the frictional force and the like accurately. Accordingly the conventional art is incapable of accurately and easily designing the golf club head demanded to have the above-described performance.